Przewalski's horses are free at last

2015-09-25 19:01:14

Ulaanbaatar /MONTSAME/ After 110 years of captivity about 500 of the remaining 2,000 Przewalski's horses in Mongolia and China are living free in segregated preserves that are intended to protect the endangered species from humans and to keep the ancient breed as genetically pure as possible. Ludovic Orlando of the University of Copenhagen's Natural History Museum of Denmark and colleagues are the first to use DNA to determine the effect of captivity on the last of Przewalski's horses. The study was reported in the Sept. 24, 2015, edition of the journal Current Biology.

The analysis investigated the genetic structure of Przewalski's horses that were as old as 45,000 years of age. Museum specimens provided a pure genetic structure of the horse that had separated from other breeds of horse that were eventually destined to be domesticated. Men first domesticated horses in China and Mongolia about 5,500 years ago. There has been considerable breeding between domestic species and Przewalski's horses. Inbreeding accelerated as the number of Przewalski's horses diminished and the horses were kept in captivity.

The researchers found that domestic horse genes actually weakened Przewalski's horses in a variety of ways. The remnants of Przewalski's horses that still survive have a higher frequency of cardiac disorders, different reproductive behavior, and metabolic changes that can be attributed to domestic horse genes. The majority of the Przewalski's horses that remain alive have at least 25 percent domestic horse DNA. Captivity, inbreeding in a limited population, and breeding with domestic horses has produced Przewalski's horses that are not as adapted to a free existence as their ancient ancestors were, wrote Paul Hamaker at Examiner magazine.